Title: Method for using an all solid-state fluorometer in industrial water system applications

Abstract: A solid-state fluorometry instrument is provided. The instrument is based on either diode laser or light-emitting diode (LED) excitation sources that are capable of being used in a wide range of applications. The solid-state diode laser based fluorometer instrument monitors fluorescent tracers, particularly suitable for industrial water sample stream applications. Using the instrument, a solid-state diode laser or light-emitting diode (LED) is used as an excitation source to excite fluorescent tracer molecules. The fluorescence resulting from the diode laser excitation is imaged with a lens onto a silicon photodiode detector. An optical filter is placed between the sample cell and the photodiode detector to reject scattered laser light. The output from the photodiode is amplified to produce an output voltage proportional to the quantity of fluorescence striking the photodiode detector. Since fluorescence is proportional to the concentration of a fluorophore present in the sample stream, continuous monitoring of a voltage output may be performed which further allows real time measurement of concentration of a fluorescent tracer present in, for example, a sample stream.